TIANJIN, China — China’s frenetic construction of coal-fired power plants has raised worries around the world about the effect on climate change. China now uses more coal than the United States, Europe and Japan combined, making it the world’s largest emitter of gases that are warming the planet.

But largely missing in the hand-wringing is this: China has emerged in the past two years as the world’s leading builder of more efficient, less polluting coal power plants, mastering the technology and driving down the cost.

While the United States is still debating whether to build a more efficient kind of coal-fired power plant that uses extremely hot steam, China has begun building such plants at a rate of one a month.

Construction has stalled in the United States on a new generation of low-pollution power plants that turn coal into a gas before burning it, although Energy Secretary Steven Chu said Thursday that the Obama administration might revive one power plant of this type. But China has already approved equipment purchases for just such a power plant, to be assembled soon in a muddy field here in Tianjin.

“The steps they’ve taken are probably as fast and as serious as anywhere in power-generation history,” said Hal Harvey, president of ClimateWorks, a group in San Francisco that helps finance projects to limit global warming.